Which equation represents a nonlinear function?

A) y = x + 7

B) y = 3x - 1

C) y = 3x^2 + 1

D) y = x - 1/2

A nonlinear function is a function with an order or the highest degree among the variables not equal to 1. In this case, we can expect the form to be that like in A, B and D. The x-variable should have an exponent of 1 to be able to be called linear. In this case, the answer to this problem should be C.